Many vasocclusive events, such as heart attacks and strokes, are caused by plaque build-ups in arteries. As one specific example, atherosclerotic plaque is known to build-up in the walls of arteries in the human body. Such plaque build-up restricts circulation and often causes problems, for example cardiovascular problems, especially when the build-up occurs in coronary arteries.
One common method for opening partially occluded body internal passages is to guide a medical device to the diseased site, where it is used to carry out the needed treatment. A guidewire is usually used for advancing a catheter device thereover via body internal passages towards the treatment site. Typically, the distal tip of the guidewire is introduced into the body of the treated subject via an incision and advanced therethrough towards the treatment site, thereby forming a path leading to the occluded site through said body internal passages. A catheter, or any other suitable treatment devices (e.g., balloon catheter, stent, rotational atherectomy device, laser device etc), may be then threaded over the guidewire and advanced through said internal passages using the guidewire as a rail.
In those cases as described above, regular guidewires are used. These regular guidewires are having a distal tip with low stiffness. The low stiffness is of the order of 1 gram, and therefore is safe for use: it cannot perforate the vessel wall or dissect into the vessel wall. These guidewires are sometimes also called a-traumatic, as they are safe and “gentle” while being threaded via the vessels.
However, sometimes the low stiffness of these guidewires is not sufficient to pass through complicated lesions, such as total or near-total occluded vessels.
Total or near-total occlusions in body internal passages can, partially or entirely, block the passage therethrough. For example, in patients who suffer from coronary chronic total occlusion (CTO), the successful performance of a Percutaneous Transluminal Coronary Angioplasty (PTCA) is a technical challenge. The factor that is most determinative of whether the physician can successfully perform PTCA on patients suffering from coronary CTO is his ability (or inability) to advance a suitable guidewire from a position proximal of the lesion to a position distal of the lesion while remaining inside the true vessel lumen (without performing perforation of the artery wall).
In some instances, such as where the occlusive matter is soft or where the body internal passage is partially occluded, the guidewire can easily be pushed through the occlusive matter itself, thereby allowing the guidewire to remain within the body internal passage. However, in other cases, such as when the body internal passage is totally occluded by hard plaque (e.g., calcified atherosclerotic plaque), the guidewire cannot cross the occlusion and may deviate to the side and penetrate through layers of the passage walls (e.g., the intima—inner layer of a vessel wall), thereby creating a neo-lumen therethrough (e.g., through the sub-intimal space—within the wall of the artery between the intima and media, or adventitia i.e. a dissection), or even completely exit said internal passage i.e. perforate the passage wall.
To enable the treatment of these complicated cases in general, and more particularly Chronical total occlusions (CTO) cases, special guidewires have been developed and introduced into market.
Such guidewires for treating CTO are generally built such that the distal portion of the guidewire is stiffer than that of a regular guidewire. This higher stiffness results in a better penetration capability into hard/calcified tissues in general and totally occluded vessels in particular. Yet, this increased stiffness, often tends to increase the risk of using them, as they can perforate the vessel wall.
The way a physician, is handling a guidewire is by manipulating the guidewire from its proximal side, i.e. from the side outside the body of the patient.
The manipulation is a combination of pushing/pulling and rotating the guidewire until it passes the partially or totally occluded zone.
When using any guidewire, including those with high stiffness, the physician has limited control over the guidewire, as he is manipulating it only from its proximal end.
The configuration of the guidewire, together with the way the physician is manipulating the guidewire, sets a limit in the performance of the said guidewire, i.e. if a physician is selecting a regular stiffness guidewire, this selection, although, will not be suitable for CTO cases. In other cases when the physician selects a high stiffness guidewire, he may be able to pass through a CTO however the risk of using such a guidewire is significantly higher, for the reasons set out above.
Currently there is no guidewire available which enables the physician to change its stiffness depending on the kind of lesion he is trying to cross while the guidewire is already threaded into the vessel. Moreover, there is no guidewire available that inherently can cross a CTO in a safe manner, due the need for new manipulations the physician is required to carry out in addition to the already existing ones.
It would be desirable to have a guidewire with more than a single stiffness zone, providing the physician with:                The capability to select the stiffness of the guidewire during the procedure, while the guidewire is already threaded into the vessel.        Manipulating the guidewire in its high stiffness mode, with an additional new mode of operation/manipulation that is inherently safe to the vessel wall and still capable of crossing CTO's.        
It is an object of the present invention, to provide a method and device for opening occluded body internal passages and of body organs, by providing a guidewire comprising at least two zones of different stiffness levels.